Original headcrab friom the Valve game Half-Life. The original .obj was passed to me by a friend. After some searching I believe the original is this one - http://thefree3dmodels.com/stuff/characters/headcrab_classic/14-1-0-844I decided it needed to be scaled to fit my cat as he is in desperate need of some extra brainpower and it won't make him any more destructive than he already is. However, as the photos show, cats are immune to headcrabs.I tweaked it in Rhino3d 4.0, modified it so it could print without support and converted it to STL. Should print well without support (aside from some caudal deformities, but hey it's a parasite) on a Cupcake. Mine was made from glow in the dark ABS.